This invention relates to a test medium and method for detecting phosphorus segregates, and more particularly, to such a method capable of rapidly and easily detecting the distribution of phosphorus in metallic materials such as continuously cast steel slabs and large-sized steel ingots.
Heretofore, segregation in large-sized steel ingots has been judged by sulfur printing. This method is by attaching photographic paper impregnated with aqueous sulfuric acid to a polished cross section of a large-sized steel ingot, thereby detecting hydrogen sulfide given off from segregated sulfur as stains on the photographic paper. This method has been widely used on the production line. Recently, however, steels subjected to low sulfide treatment and Ca treatment, such as steels resistant to hydrogen embrittlement cracking, have been put into practical use, and much progress has been made in the art to manufacture high purity steel and to prevent segregation in continuous castings. Such advanced steels having extremely low sulfur contents make it difficult to detect solidification segregates by the conventional sulphur printing.